This invention relates generally to fluid shut off valves and more specifically to an automatic shut off valve using magnetic actuation.
The modern aircraft lavatory uses the flow of disinfectant fluid or a powerful pump to remove waste from a toilet into a waste holding tank. During ground maintenance the waste tank is emptied and sanitized. Sanitation is especially important to kill any infectious disease agents potentially carried in human waste. The emptying and sanitizing processes are typically performed by airport ground crews using a lavatory cart. The cart includes a supply of disinfectant fluid as well as a disposal tank. Disinfectant fluid is pumped into the aircraft waste holding tank after waste from the flight is drained.
In order to do an effective job of sanitizing the aircraft waste storage tank, it is desirable to fill the waste storage tank up to a specific level. Filling to a high level has many potential drawbacks if overfilling occurs. Overfilling can create spillage of disinfectant fluid, potentially contaminated with human waste. Spilled disinfectant fluid can freeze at high altitudes, creating solid projectiles, sometimes referred to as blue ice, which are potentially dangerous to the aircraft, especially its engines. Disinfectant fluid is harmful to the aircraft structure and electronics. Disinfectant fluid also includes a strong smelling detergent which when spilled on the interior of the aircraft via overfilling the toilet is objectionable, thus, it is desirable to minimize spills.
A valve which can automatically prevent overfilling of the waste holding tank is desired. An additional desire is to provide a valve with automatic shut off for use during the filling operation in combination with a backflow prevention device for use during normal operations.
The present invention is directed to an automatic shut off valve and to an aircraft lavatory system which may be sanitized while avoiding any overfilling of the sanitary waste holding tank.
In one embodiment the invention provides a shut off valve for regulating fluid flow which includes an inlet passage in intermittent fluid communication with an outlet passage, a magnetic flapper body movable between a rest position and a seal position between the inlet passage and the outlet passage and a magnetic actuator that moves the flapper body toward a seal position, thus, preventing fluid communication between the inlet passage and the outlet passage.
In another embodiment the invention provides a lavatory system for use on an airplane which includes one or more toilets, each toilet including a drain passage for disposal of sanitary wastes. The system also includes a waste tank attached to the drain passages from said toilets, a shut off valve for regulating flow of disinfectant fluid used to rinse the waste tank, a vertically canted tube in fluid communication with the waste tank, and a magnetic float within the tube whereby the float rises and falls in response to level changes within the waste tank. The shut off valve includes an inlet passage in intermittent fluid communication with an outlet passage, which directs fluid to the waste tank. The valve also includes a magnetic flapper body movable between a rest position and a seal position between the inlet passage and the outlet passage. When a predetermined level is reached in the waste tank, the magnetic float comes within the proximity of the magnetic flapper body, and the flapper body is moved from a rest position and, with the assistance of fluid flow pressure into a seal position.
The present invention provides numerous advantages not realized in the prior art. First, the invention provides a no-spill filling system, thus, avoiding potential freezing of spilled fluid and avoiding the problems associated with a spilled, highly aromatic and corrosive fluid. The invention also provides a shut off valve which may be actuated magnetically, avoiding the need for a mechanical actuator. As a result, the valve may be constructed with fewer parts and seals which minimizes potential failures. Additionally, the shut off valve within the system functions automatically thereby eliminating the need for airline ground crews to consistently check the level of disinfectant fluid being fed into the waste tank during sanitizing operations. Thus, the valve serves as a backup if the ground crew forgets to shut off the inlet supply at the appropriate level from the truck.
These and other features, aspects and advantages of the present invention will be fully described by the following description, appended claims, and accompanying drawings.